Ammunition projectile having improved aerodynamic profile and method for manufacturing same

ABSTRACT

A solid projectile for a firearm having a central cylindrical section defining a bearing surface and an integral, coaxial leading section tapered into a uniform conical surface, the apex at the distal end thereof projecting to a point or apex. The apex angle of the conical surface of the leading section of the projectile is within the range of 20°-40° of arc.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention generally relates to projectiles intended to be fired from firearms, and more particularly to a projectile that includes a specially contoured leading section that is designed to enhance the aerodynamic properties of the projectile and the method of manufacturing the projectile.

2. Description of the Prior Art

The prior art discloses many attempts to improve the basic design of projectiles intended for use with firearms. With the interest that exists in the field of sport target shooting and with the interest of outdoorsmen, hunters and the like, substantial attention has been given to enhance the external ballistics of the projectile through the design of bullets that yield greater accuracy and range. In addition to accuracy and range, concern has been paid to increasing the velocity of a projectile or a bullet for a given charge. Increasing the velocity of the projectile as well as reducing the drag of the projectile depends very much on the aerodynamic qualities of the projectile itself.

The geometry of a projectile for a firearm is generally divided into symmetrical sections. The body or shank of the projectile is that part of the projectile that comes into full contact with the barrel rifling of the firearm. The cylindrical portion of the projectile is generally referred to as the bearing surface. The prior art generally refers to the term “ogive” to describe the specific point where the leading section of the projectile begins. This is typically where the bearing surface ends and the leading section begins. While the term “ogive” is often used to describe the particular point on the projectile where the leading section reaches the full projectile diameter of the central section of the projectile, the ogive properly refers to the entire curve of the projectile from the distal tip of the projectile to the central section thereof.

As disclosed in the prior art, the ogive of a projectile is usually characterized by the length of its radius. The radius is often given in calibers. The ogive profile of the leading section of a projectile for a firearm is generally described as a tangent ogive design or a secant ogive design. The prior art defines a tangent ogive design as one where the intersection of the central section of the projectile and the radius of the ogive blend together at a tangent point. In a secant ogive design, the point of intersection between the central and leading sections of the projectile is not tangent, the ogive radius being a secant of the arc circle of the ogive.

Irrespective of whether a projectile is categorized as a tangent or a secant ogive design, the distal tip of the ogive is referred to as a meplat. The shape of the meplat has a great effect on external ballistics. The shape of the meplat can also have an effect on terminal ballistics and performance. A representative sample of prior art discloses a projectile that employs an ogive geometry and a relatively short length of the extreme distal tip of the ogive portion of the projectile is further infolded toward the center line of the projectile by a relatively few degrees thereby defining a tapered tip having a void volume in the most distal portion of the open end of the projectile defining a meplat cavity. This configuration can adversely affects the aerodynamic efficiency of the projectile. As the meplat cavity is enlarged, the aerodynamic efficiency of the projectile deteriorates.

The present invention overcomes the disadvantages of the designs disclosed in the prior art by utilizing a leading section of a projectile that comprises ogive segment geometry constituting a secant ogive design adjacent the central section of the projectile and a conical segment extending from the secant ogive segment at the distal end of the projectile. The apex angle of the surface of the conical segment at the distal end of the projectile is within the range of 20°-40° of arc. The use of a leading section comprising a secant ogive design and a conical segment at the distal end will, by definition, require smaller point angles to create a projectile that will be optimized based on the purpose and use of the projectile.

SUMMARY OF THE INVENTION

The present invention comprises a geometrical configuration for a projectile intended to be used with firearms having a geometrical configuration that improves the aerodynamic efficiency of the projectile and the method for manufacturing the projectile. The projectile comprises a preformed slug or bullet core that can be made of lead but is preferably a lead core in a deformable copper jacket. The projectile comprises a substantially cylindrical central section having an outer bearing surface is adapted to come into full contact of the barrel rifling of the firearm. The cylindrical central section extends forwardly into a leading section that is coaxial with the central section. The leading section comprises a secant ogive segment that intersects with the bearing surface of the central section at an ogive radius that is a secant of the arc circle of the ogive. The secant ogive segment extends into a conical segment at the distal end of the leading section. The surface of the conical segment of the leading section is projected into an apex that is uniformly disposed about the common axis of the central and leading sections of the projectile. The apex angle of the surface of the conical segment is within the range of 20°-40° of arc. The conical segment is approximately 20% of the axial length of the leading section at the distal end of the projectile. The diameter of the meplat at the distal tip of the conical segment of the projectile is uniformly disposed about the common axis of the leading and central sections of the projectile and the area thereof is substantially less than the meplat area of a projectile employing a tangent ogive design for the leading section.

It is an object of the present invention to provide a projectile for a firearm having enhanced external ballistics.

It is another an object of the present invention to provide a projectile for a firearm having improved aerodynamic stability.

It is still another object of the present invention to provide an improved projectile for a firearm that employs a secant ogive design that reduces aerodynamic drag.

It is still yet another object of the present invention to provide a projectile for a firearm that has a meplat of reduced area to enhance aerodynamic properties.

It is still yet another object of the present invention to provide an improved design for a projectile intended for use in a firearm that is inexpensive and easy to fabricate.

The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objectives and advantages thereof, will be better understood from the following description considered in connection with the accompanying drawing in which a presently preferred embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawing is for the purpose of illustration and description only, and is not intended as a definition of the limits of the invention.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 illustrates a side view of an enlarged scale projectile for firearms in accordance with the present invention.

FIG. 2a is a schematic view of a prior art projectile having a tangent ogive design adjacent the central, cylindrical section of the projectile.

FIG. 2b is a schematic view of a prior art projectile having a secant ogive design adjacent the central, cylindrical section of the projectile.

FIG. 3 is an exploded, perspective elevation view of a die assembly used to manufacture projectiles in accordance with the present invention.

FIG. 4 is a cross-sectional view of the die piece shown in FIG. 3 used to manufacture projectiles in accordance with the present invention.

FIG. 5 is an end view of the die piece shown in FIG. 1 illustrating the conical surface to be impressed on the distal end of a projectile in accordance with the present invention.

FIG. 6 is a partial cross-sectional view of the present invention projectile forming die showing the structural elements thereof in their assembled relation.

DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENT.

The present invention design for the improvement of a projectile for a firearm can be best understood by initial reference to FIGS. 2a and 2b which illustrate prior art projectile designs employing a tangent ogive design and a secant ogive design, respectively. The design of a bullet or projectile for firearms must solve two basic problems. Firstly, while the projectile is in the barrel of a firearm, it must form a seal with the firearm's bore. The projectile must also engage the barrel rifling without damaging or excessively fouling the firearms bore, and, without distorting the projectile which could reduce accuracy. The interactions between the projectile and the bore of the firearm is generally referred to as “internal ballistics.” The present invention relates to the principles affecting the projectile once it leaves the barrel of the firearm, this being generally referred to as “external ballistics.” The geometry of a bullet or projectile can be broken down into symmetrical sections. The body or central section of a projectile is that part of a projectile that comes into full contact with the barrel rifling.

The term “ogive” is commonly used to describe the specific point where the curving part of the leading section of the projectile begins. The terms “ogive” or “ogive profile” are used to describe the entire leading curve section of a projectile. FIG. 2a illustrates a prior art design of a projectile employing what is referred to as a “tangent radius ogive.” In a tangent ogive design, the interface 30 between central section 31 and leading section 30 is at the tangent of the tangent radius 34, the curved profile for leading section 33. FIG. 2b illustrates a prior art design employing a secant ogive design. In a secant ogive design, the intersection 35 between the ogive or leading section 37 and central section 36 does not flow together smoothly. The point of intersection 35 is not tangent, the ogive radius being a secant of the arc circle of the ogive. The difference between a tangent ogive design and a secant ogive design is that the latter provides a longer, tapered curvature to leading section 37. The design of the present invention improves the external ballistics of the projectile by modifying the geometry of the leading section of the projectile.

Referring to FIG. 1, a projectile 40 in accordance with the present invention comprises leading section 41, central section 42 and boat tail 43, all axially aligned along longitudinal center line 44. Central section 42 is uniformly cylindrical and is adapted to come into full contact with the barrel rifling. Leading section 41 axially extends forwardly from central section 42. The interface 45 between leading section 41 and central section 42 is a secant ogive design that displays the tapered extended profile as described with respect to FIG. 2b . The boat tail or trailing section 43 axially extends from central section 42 opposed to leading section 41.

Contrary to the designs taught by the prior art, a conic segment 46 extends forwardly from base segment 47 of leading section 41. The surface 48 of conic segment 46 projects to apex 49 on longitudinal center line 44. The conic segment 46 is truncated at the distal tip of the ogive to form a meplat 50 that is inwardly folded along the center line to form a conventional meplat cavity (not shown). The apex angle 51 of conic surface 48 is in the range of 20°-40° of arc. To optimize the aerodynamic properties of projectile 40, the axial length of conical segment 46 is approximately 20% of the total axial length of leading section 41.

An understanding of the projectile forming die employed to manufacture the present invention projectile 40 can be best seen by reference to FIGS. 3-6, inclusive, the die assembly generally being designated by reference numeral 60. Die assembly 60 employs a cylindrical die block 61 having external threads 62 with which locking ring 63 is engaged in order to mount and stabilize die block 61 to a conventional reloading tool (not shown). A lower central bore 64 is axially formed in the lower portion of the die block 61 for receiving projectile seating element 65. Projectile seating element 65 has a cylindrical outer body 66 adapted to slidably engage with lower central bore 64. The lower portion of projectile seating element 65 extends axially downwardly into an engagement rim 67 which is coupled to conventional reloading tools. After engagement rim 67 is secured to the reloading tool, lock ring 63 is rotated downwardly against the reloading tool to maintain stability between the reloading tool and die block 61. A projectile seating bore 68 is axially disposed in the upper portion of projectile seating element 65 for receiving and supporting projectile 40. To provide consistent engagement of seating element 65 within die block 61 during the manufacturing process, the upper end 70 of projectile seating element 65 adjacent seating bore 68 is tapered inwardly and is adapted to be positioned adjacent beveled surface 71 contiguous with central bore 64 of die block 61. An upper threaded central bore 75 is axially disposed into die block 61 in opposition to lower central bore 64 and is adapted to receive threaded shaft 76 of die cap 77. When die cap 77 is engaged within upper threaded central bore 75, die cap 77 will be in axial alignment with projectile seating bore 68.

The conic segment 46 of leading section 41 of the present invention projectile is formed with die piece 80. As can be seen best in FIG. 4 and FIG. 5, die piece 80 is a cylindrical member having a base 81 perpendicular to the axis 82 of the die piece, a conical depression 83 being disposed into base 81 of die piece 80 consistent with the specifications of conic section 46 of leading section 41 of projectile 40. The upper end of die piece 80 extends into a tapered conical positioning surface 84, the apex 85 of conical positioning surface 84 being axially aligned with the apex 86 of conical depression 83. A cylindrical bore 89 is axially disposed into threaded shaft 76 adapted to slidably receive die piece 80. The upper end of cylindrical bore 89 is formed into a conical receiving surface 90 that is adapted to engage conical positioning surface 84 of die piece 80 to maintain die piece 80 in axial alignment with the projectile seating base 68 during use.

The method by which the present invention projectile can be formed can best understood by reference to FIGS. 3 and 6. The first step is to mount engagement rim 67 of projectile seating element 65 to a conventional reloading tool (not shown). Die block 61 is mounted upon projectile seating element 65 slidably engaging lower central 64 of die block 61 with outer surface 66 of projectile seating element 65. Once in place, lock ring 63 secures the coupling between die block 61 and the reloading tool. A preformed slug or bullet core that is to be formed into the present invention projectile 40 is positioned within projectile seating bore 68 of projectile seating element 65. As can be best seen in FIG. 6, boat tail 43 of projectile 40 is disposed against the bottom surface of projectile seating base 68. After engaging die piece 80 within cylindrical bore 89 of threaded shaft 76, threaded shaft 76 is rotatably engaged to upper threaded central bore 75 of die block 61. Die cap 77 and the integral threaded shaft 76 are rotatably lowered until the leading section 41 of projectile 40 is engaged with conical depression 83 of die piece 80. The die cap 77 and integral threaded shaft 76 are rotatably lowered into die block 61 causing the surface of the conical depression 83 of the piece 80 to impose compressive force against conical surface 48 until the axial length of conical segment 46 is approximately 20% of the total axial length of leading section 41 of projectile 40 and conic segment 46 and meplat 50 define an apex angle 51 that is within the range of 20°-40° of arc. 

1. An improved firearm projectile comprising: a) a cylindrical central section having an outer surface; b) a trailing section in axial alignment with the central section and being integrally formed with the central section and projecting rearwardly therefrom; and c) a leading section in axial alignment with the central section comprising an axially aligned ogive base segment and a conic segment, the conic segment being integral with the ogive base segment of the leading section and extending forwardly therefrom, the base segment of the leading section being integral with the central section and extending forwardly therefrom, the conic section having a conical surface defined by an apex angle relative to the axis of the leading section being in the range of 20°-40° of arc.
 2. (canceled)
 3. An improved firearm projectile as defined claim 1 wherein the axial length of the conic segment is approximately 15-20% of the total axial length of the leading section.
 4. (canceled)
 5. An improved firearm projectile comprising: a) a cylindrical central section having an outer surface; b) a trailing section in axial alignment with the central section and being integrally formed with the central section and projecting rearwardly therefrom; and c) a leading section in axial alignment with the central section comprising an axially aligned secant ogive base segment and a conic segment, the conic segment being integral with the secant ogive base segment and extending forwardly therefrom, the conic segment having a conical surface defined by an apex angle in the range of 20°-40° of arc relative to the axis of the leading section, the axial length of the conic segment being in the range of 15-20% of the total axial length of the leading section.
 6. A method for manufacturing an improved firearm projectile comprising: a) providing a die block having an upper cylindrical bore and a lower cylindrical bore in axial communication with one another; b) providing a deformable projectile core having a cylindrical central section integral with a curved leading section extending forwardly from the central section; c) providing a projectile seating element having an upper axial seating bore adapted to be slidably engaged within the lower cylindrical bore of the die block; d) positioning the deformable projectile core within the seating bore of the projectile seating element; e) providing a die piece adapted to be slidably engaged within the upper cylindrical bore of the die block, the die piece having an axially aligned conical receiving surface disposed in the lower end thereof; f) positioning the die piece within the upper cylindrical bore until the conical receiving surface of the die piece is in engagement with the curved leading section of the deformable projectile core; and g) deforming the curved leading section of the projectile core until the upper portion of the leading section of the projectile core into a conic section defining the conical receiving surface of the die piece.
 7. An improved firearm projectile manufactured by the method of claim
 6. 